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Due to the loop distance of double circuit transmission line on the same tower is small, the electromagnetic coupling and electrostatic coupling between the power failure line and the running line are greatly enhanced, and higher induced current and induced voltage are generated on the power failure line. At the same time, the line is erected without transposition, the line’s three-phase parameter is asymmetrical, and the induced current and induced voltage show obviously phase separation characteristics. The paper apply transient simulation software EMTP to simulate the induced current and induced voltage under different line lengths, transmission power flow and phase sequence arrangement, which provides a reference for the design, planning and operation of 500 kV double lines on the same tower in the regional power grid.

The capacitive current feedback active damping strategy has a limited damping region. When the grid-side impedance is large, the digital control inductor–capacitor–inductor (LCL) grid-connected inverter system with grid-side current loop control and capacitive current feedback active damping cannot run stably. To address this issue, this study proposes an improved capacitive current feedback active damping strategy, namely the capacitive current fractional proportional–integral feedback strategy (CCFPIFS), which increases the upper-frequency limit of the system damping region and approaches to the Nyquist sampling frequency. Furthermore, this study analyses the constraints of fractional-order proportional–integral controller parameters to ensure the stability of the system. The simulation analysis is performed by Simulink. The experimental results are consistent with theoretical expectations. Consequently, the proposed CCFPIFS can not only achieve better control performance and improve the robustness of the LCL grid-connected inverter system, but also improve the output power quality of the system. This damping strategy can make the LCL grid-connected inverter system work stably under the environment of high grid impedance.

U ovom diplomskom radu objašnjene su teorijske osnove jednopolnih kvarova u elektroenergetskoj mreži. Fazorskim dijagramima prikazane su struje kvarova u distribucijskim mrežama za različite tipove mreža, odnosno različite izvedbe uzemljenja zvjezdišta transformatora. Prikazana su mjerenja kapacitivnih struja u pojedinim 35/10(20) kV trafostanicama. Provedena je analiza kvarova u distribucijskoj mreži u programskom paketu Neplan, te su dobivene minimalne struje jednopolnog, dvopolnog i tropolnog kratkog spoja po pojedinim izvodima trafostanica. Dane su predložene postavke nadstrujnih releja za 35/10(20) kV trafostanice u kojima su bila prethodno opisana provedena mjerenja kapacitivnih struja. Kao konačan ishod ovog rada uspoređivane su tablično postavke zemljospojne zaštite sa mjerenim kapacitivnim strujama kvara, te je ustanovljeno da je zaštita pravilno podešena. This paper explains the theoretical foundations of single - pole failures in the power grid. Phasor diagrams show fault currents in distribution networks for different types of networks and different grounding systems of transformer neutral point. Measurements of capacitive currents in individual 35/10 (20) kV substations are presented. An analysis of faults in the distribution network in the Neplan software was performed, and the minimum structures of single-phase, phase to phase and three-phase short circuits were obtained for individual substation. The proposed settings of overcurrent relays for 35/10 (20) kV substations are given, in which the measurements of capacitive currents are previously described. As a final result of this paper, the table settings of earth fault protection were compared with the measured capacitive fault currents, and it was found that the protection was set correctly.

Interleaved converters are a typical solution to enhance a current capacity and to reduce current ripples of an input or output port. Conventional interleaved LLC resonant converters need additional switches and passive components with a feedback control loop for active current balancing, increasing the circuit complexity and cost. This paper proposes a novel three-phase interleaved LLC resonant converter with an automatic capacitive current balancing capability. Two flying capacitors are added to a conventional interleaved LLC resonant converter in order to realize not only the automatic capacitive current balancing but also the reduced switch voltage stresses and asymmetric resonant operations that contribute to reducing rms currents as well as copper losses of transformers. The detailed operation analysis, including the capacitive current balancing mechanism and gain characteristics derivation, are performed. The experimental verification using a 1-kW prototype demonstrated that the automatic capacitive current balancing could be achieved despite the significant mismatch in transformers' parameters.

One of the most serious possible faults in power systems is transformer limited fault (TLF), in which transient recovery voltage (TRV) characteristics is determined by the closest transformer to the circuit breaker and due to the immense variety of transformers; performing experimental tests to determine TRV in all cases is impossible. Therefore, simulation is recommended. Purpose of this paper is to review existing methods for transformers modeling in TRV studies and compare their results with the measurement results. Three different models including impedance model, simplified model and frequency dependent model are studied. All models are obtained using transformer FRA results. Then modelling is done for three separate transformers. Also the application and proposed guidelines of model selection are suggested. Finally, TRV simulations are performed in EMTPWorks using capacitive current injection method. As a result, amplitude factor and TRV frequency are calculated for each model and simulation and measurement results are compared. Keywords: Transformer modelling, Transient recovery voltage, Transformer limited fault, FRA test, Current injection method, TRV frequency

It remains unclear how spike-wave discharges (SWDs) in electroencephalograms (EEGs) arise, although some researchers believe that there is some focus in the deep brain and others have pointed out the importance of the interaction between the thalami and cortices. My previous work hypothesized that possible resonance in white matter may induce extremely large amplitude discharges in an EEG, which are associated with SWDs. The visual evoked potential (VEP) technique revealed a resonance phenomenon that supports this hypothesis. In this research, I theoretically reconsidered the resonance phenomenon based on the cable theory modified by considering dielectric dispersion. If both the resistive and capacitive currents in the dielectric material contribute to conduction along an axon, we can show that the current amplitude has a single maximum at a certain frequency and this amplitude depends on the geometrical ratio of capacitance to resistance. The frequency can be common for any axon in a wide white-matter area. We can infer that SWDs will arise, when the frequency generated by the thalamic reticular nucleus neurons coincides with the resonance frequency of the white matter. The resonance frequency predicted by the modified theory is close to the known frequency of the SWDs.

The article presents the results of a comparative analysis of the accuracy of existing methods for determining the capacitive current relative to the ground for the 6 kV distribution network of a mining enterprise. The calculation of capacitive currents flowing in the outgoing connections of the electric network in the single-phase ground fault mode is performed using various existing methods. An experiment of a single-phase ground fault in an active distribution network was conducted, based on the results of which the obtained values of capacitive currents made it possible to determine the errors of known calculation methods.

Данная работа посвящена созданию методик оценки работы дифференциальной защиты линии в Ð¿ÐµÑ€ÐµÑ Ð¾Ð´Ð½Ñ‹Ñ Ð¿Ñ€Ð¾Ñ†ÐµÑÑÐ°Ñ . Приведено описание построения измерительной и логической части дифференциальной защиты линии, проведен анализ реализации ÑÑƒÑ‰ÐµÑÑ‚Ð²ÑƒÑŽÑ‰Ð¸Ñ ÐºÐ¾Ð¼Ð¿Ð»ÐµÐºÑ‚Ð¾Ð² защиты Ñ€Ð°Ð·Ð»Ð¸Ñ‡Ð½Ñ‹Ñ Ð¿Ñ€Ð¾Ð¸Ð·Ð²Ð¾Ð´Ð¸Ñ‚ÐµÐ»ÐµÐ¹ в данной отрасли. Рассмотрены и исследованы причины снижения эффективности или возникновения ложной работы дифференциальной защиты линии. Предложены методики для анализа Ð´Ð°Ð½Ð½Ñ‹Ñ Ð¿Ñ€Ð¸Ñ‡Ð¸Ð½ в отдельности или Ð¸Ñ ÐºÐ¾Ð¼Ð±Ð¸Ð½Ð°Ñ†Ð¸Ð¸. Анализ проводился с помощью подготовленного программного комплекса, созданного на основе графического программирования в среде моделирования LabView фирмы National Instruments. Экспериментальные данные Ñ€Ð°Ð·Ð»Ð¸Ñ‡Ð½Ñ‹Ñ Ð°Ð²Ð°Ñ€Ð¸Ð¹Ð½Ñ‹Ñ Ð¸ ÑƒÑ‚ÑÐ¶ÐµÐ»ÐµÐ½Ð½Ñ‹Ñ Ñ€ÐµÐ¶Ð¸Ð¼Ð¾Ð² работы защищаемого объекта извлекались из созданной энергосистемы в среде моделирования MatLab Simulink. На основе Ð¾ÑÑƒÑ‰ÐµÑÑ‚Ð²Ð»ÐµÐ½Ð½Ñ‹Ñ Ð¸ÑÑÐ»ÐµÐ´Ð¾Ð²Ð°Ð½Ð¸Ð¹ по предложенной методике дается оценка Ð¿Ð¾Ð»ÑƒÑ‡ÐµÐ½Ð½Ñ‹Ñ Ñ€ÐµÐ·ÑƒÐ»ÑŒÑ‚Ð°Ñ‚Ð¾Ð² работы дифференциальной защиты линии в Ð¿ÐµÑ€ÐµÑ Ð¾Ð´Ð½Ñ‹Ñ Ð¿Ñ€Ð¾Ñ†ÐµÑÑÐ°Ñ ., This work is devoted to the creation of methods for evaluating the operation of differential line protection in transients. The description of the construction of the measuring and logical part of the differential protection of the line is given, the analysis of the implementation of existing protection kits from various manufacturers in this industry is carried out. The reasons for the decrease in the efficiency or the occurrence of false operation of the differential protection of the line are considered and investigated. Methods for analyzing these causes individually or in combination are proposed. The analysis was carried out using a prepared software package created on the basis of graphical programming in the LabVIEW modeling environment of National Instruments. Experimental data of various emergency and heavy operation modes of the protected object were extracted from the created power system in the MatLab Simulink simulation environment. Based on the studies carried out according to the proposed method, an assessment of the obtained results of the differential protection of the line in transients is given.

Capacitive bioanodes can be used to improve current production in bioelectrochemical systems for combination of energy recovery and wastewater treatment. Here, we compared current production in fixed and moving bed capacitive bioanodes. For fixed bed bioanodes, the recovered charge was studied as a function of the discharge current collector position and the thickness of the granule bed. The most capacitive charge was recovered from the current collector closest to the membrane. Increasing bed thickness from 5 mm to 10 mm resulted in a 1.6 times higher current density per membrane area. These findings were used to improve the design of a moving bed reactor, where granules moved through a discharge cell and were recirculated using a gas lift. The moving bed produced a current of 43 A/m2, about 2 times the fixed bed current over the full charging and discharging cycles. The relatively short discharge time and long charging time of the moving bed as compared to the fixed bed bioanodes led to higher capacitive currents. The design of the discharge cell and the ratio between charge and discharge times can be further optimized to make better use of stored charge of the granular capacitive bioanodes.

The nowadays bigger part of the medium voltage power grids is a cable part and the earth-fault currents increase. When the capacitive current at single phase to earth current is greater than l0 A, the neutral of the grids has to be grounded. The aim of the paper is to investigate eventual voltages (touch and step) at place of the earth fault in the grids when the soil resistivity has high values. To be possible to analyze the acceptability of the voltages' values they were compared with values, received using formulas from an international standard of IEEE.

In view of problem of limitations or non selective leakage protection in capacitive current compensation system, an adaptive full compensation domain selective leakage protection method based on phase difference of zero sequence voltage and zero sequence current was studied. Principle of the method was introduced, and hardware circuits of the method were introduced in details. The test results showed that the method can self-adaptive select single-phase leakage fault circuit from full compensation domain.

SF 6 /N 2 mixed gas, as a typical binary mixed gas with synergistic effect, is a simple and effective SF 6 environmental protection measure. It has been gradually applied to gas-insulated power equipment such as GIS. In order to develop a mixed-gas 126 kV GIS disconnecting switch, breaking characteristics under typical operation conditions are carried out. A circuit breaking test for bus-transfor current was established, and a bus-transfor current breaking test was carried out. It was found that under different conditions, the arc time of the mixed gas was significantly longer than that of SF 6 . Under the condition of 30V/1600A, the arc time of 28% mixed gas is increased by about 29% compared with SF 6 . The arcing time of the mixed gas with 40% mixing ratio is similar. The arcing time will increase when the gas pressure decreases. The operation speed of the disconnecting switch has a small effect on the breaking. After 100 tests, the contactor was slightly ablated after the 30V/1600A test but still passed the test. However, the contactor was severely ablated under the 100V/1600A breaking condition and failed the test. A small capacitive current breaking test circuit was set up, and a small capacitive current breaking test was carried out. It is found that the mixing ratio, gas pressure, and switching operation speed have the same effect on the arcing time as the bus-transfor current breaking test. Compared with SF 6 , the breaking performance is significantly reduced. The arcing time of 28% mixed gas in the 126kV test is increased by about 25%. No insulation discharge occurred after 50 tests, and it was judged that the test passed. In summary, the breaking performance of the mixed gas is significantly lower than SF 6 , which will make the arcing time and the contactor ablation increase, and even the breaking failure. An improved method of adding copper-tungsten arcing contactor was proposed, after which the test sample was improved, and the type test was passed.

Glyphosate is an organophosphorus herbicide that is applied to the leaves of plants and crops to kill broadleaf plants and grasses. In this paper, for the first time, a field deployable, user-friendly, portable and rapid electrochemical pesticide sensing system is presented that can screen for glyphosate in produce run-off/extract. ElectrochemSENSE comprises the following parts: A polymer based disposable substrate with metallized electrodes that are surface treated with polyclonal antibodies of glyphosate and a custom electronic reader capable of reporting pesticide contamination. Utilizing the principles of capacitive current changes due to selective binding of glyphosate to its capture probe, reporting was achieved rapidly (in under 5 min). ElectrochemSENSE was tested to screen for glyphosate concentrations on produce samples above or below the globally accepted metric criterion, otherwise known as the Maximum Residue Level (MRL). Experiments were conducted on 4 produce types-apples (MRL: 0.2 ppm), strawberries (MRL: 0.2 ppm), bell peppers (MRL: 0.1 ppm) and carrots (MRL: 5 ppm). To further add functionality and increase prediction accuracy- a machine learning binary classifier was integrated with the device as a proof-of-concept so that sensor's response can be trained and characterized to perform with high accuracy, thereby serving as an analytics medium which minimizes error rate. Utilizing this system-the sensor's limit of detection has been determined to be 0.01 ppm (10 ng/mL) considering the permissible Field Operating Range (FOR) for glyphosate residue in various tested produce.

At present, multibreak vacuum circuit breakers (VCBs) have attracted more attention in order to meet the requirement of the environmental protection, high-voltage VCBs, capacitive current switch-off, and the dc current breaking. The advantages and disadvantages of multibreak VCBs are analyzed and discussed according to the research status. Then, the synergy effect of multibreak VCBs is proposed, which is the interaction among the arc memory, current zero characteristic, and the postarc characteristic. The target of the synergy effect is the synergy between the dynamic dielectric recovery strength and the postarc dynamic voltage distribution. The maximum breaking capacity can be obtained in the above-mentioned synergy control. Finally, the optimization design, key technology, basic theory, and application of multibreak VCBs are discussed. With the development of multibreak VCBs, it will be widely used in high-voltage level, HVdc, and pulsed-power switchgear in the future.

With the higher penetration of renewable energy, the influence of grid equivalent distribution cable impedance on grid-connected inverter stability is attracting increasing attention. In order to suppress the interaction between grid distribution cable impedance and output impedance of the grid-connected system, the active damping strategy is often used. When a capacitive current loop is used, the damping coefficient increases with the grid impedance increasing. However, the excessive damping coefficient will cause the unstable operation of the system. In order to enhance the robustness of the system, a novel control strategy which is suitable for wide-range grid impedance variation is proposed. In this strategy, the capacitor current inner loop is combined with the grid current inner loop, and grid voltage feedforward is included. Since the virtual impedance, active damping and voltage feed-forward are normalized, the changing tendency of the damping coefficient of the grid-current inner loop is opposite to that of capacitor current inner-loop. The overall damping coefficient of the system remains relatively constant when the grid impedance changes, and this effectively suppresses the resonance of the system. In this paper, the method is analyzed and the parameters are designed and optimized. Finally, the simulation and experiment are presented to verify the analysis.

In this paper, a nonisolated two-phase interleaved LED driver with capacitive current sharing is presented. In the proposed LED driver, the current sharing capacitor can be used to balance the input inductor currents and the LED currents. Furthermore, only one grounded LED string current is sensed and controlled. Moreover, under the interleaved control, the input current ripple can be reduced. Finally, the operating principles, analyses, and experimental results are provided to verify the effectiveness of the proposed LED driver.

The combination of high-frequency ac drive and capacitors offers an attractive passive current balancing solution for multistring light-emitting diodes (LED) lighting systems due to the advantages of compactness, high efficiency, and ease of modularity. Given that frequency-controlled resonant converters are commonly used as high-frequency ac drivers, the conventionally used switching frequency modulation could impair the effectiveness of capacitive balancing as the impedance of the balancing capacitors is a sensitive function of the switching frequency which is constantly varied for the purpose of output voltage regulation. In this paper, a constant-frequency capacitive impedance current balancing method is proposed. Compared to the conventional method, output voltage regulation of resonant converter is achieved by modulating the resonant frequency of resonant tank by switch-controlled capacitor (SCC) technique, which gives rise to constant balancing capacitor's impedance and constant LED current over a wide range of load conditions. Its implementation in an $LCC$ resonant network is studied in this paper and a systematic design procedure of a SCC-based constant-frequency $LCC$ resonant converter is presented. The effectiveness of the proposed method is experimentally verified by a 70-W experimental prototype.

A dimmable LED driver along with an extendable series structure and interleaved capacitive current sharing is presented herein, the LED connection of which is changed from the traditional series structure to the proposed parallel structure. The number of LED strings can be extended. As the number of LED strings is increased, the output voltage of this LED driver and the voltage stress on the main switch are ideally not influenced. Moreover, only one current sensor is needed to achieve current control and dimming. In this paper, the basic operating principle of the proposed LED driver is described and analyzed. Finally, the effectiveness of this LED driver is demonstrated by experiment based on the field-programmable gate array (FPGA).

Over the last years industry and home sector has grown in Latvia. Industry and home sector developed mostly around Riga - capital of Latvia. This caused an expansion of the 20 kV networks therefore appear necessity to build new 20kV networks. The new 20kV network in densely populated areas is built as cable network. Besides since 2011 existing overhead lines which are located in densely populated areas is going to change to cable lines. Increasing of cable lengths brings increment of earth fault capacitive current. Main aim of this article is show distributed compensation application in Latvia's 20kV networks.

Effectively grasping the basic data of capacitive current of power distribution network and regularly checking arc suppression coil device are important tasks to ensure the safe and stable operation of distribution network. Therefore, a method of on-line measuring capacitive current of power distribution network (signal injection method) is introduced. The correctness of the principle is verified by simulation analysis. However, in the actual power distribution network measurement, the method has the practical engineering problem of serious deviation of measurement results. Therefore, a detailed analysis is carried out.

This paper presents current flow in cable screens and a cable screen earthing system. Moreover, the paper presents the methodology for the detection of problems in cable screens, such as open phase in a cable screen and high contact resistance of a cable screen in a cable joint. The is based on cable screen current measurements and allows for localization of the erroneous connection&ndash, high contact resistance or open phase. The phenomenon is simulated in PowerFactory Software. Moreover, exemplary cable screen current measurements are presented.

Виконано аналіз розподілу ємнісних струмів в витках багатошарових обмоток високовольтних автотрансформаторів напруги. Визначено відмінність розподілу ємнісних струмів для першого шару витків та всіх інших шарів обмотки. Запропонований метод врахування впливу ємнісних струмів в обмотці високовольтного автотрансформатора напруги на розподіл загального спадання напруги по витках обмотки.

Our objective was to describe the electrophysiological properties of the extracellular action potential (AP) picked up through microelectrode recordings (MERs). Five patients were operated under general anesthesia for centromedian deep brain stimulation (DBS). APs from the same cell were pooled to obtain a mean AP (mAP). The amplitudes and durations for all 2/3 phases were computed from the mAP, together with the maximum (dVmax) and minimum (dVmin) values of the first derivative, as well as the slopes of different phases during repolarization. The mAPs are denominated according to the phase polarity (P/N for positive/negative). We obtained a total of 1109 mAPs, most of the positive (98.47%) and triphasic (93.69%) with a small P/N deflection (Vphase1) before depolarization. The percentage of the different types of mAPs was different for the nuclei addressed. The relationship between dVmax and the depolarizing phase is specific. The descending phase of the first derivative identified different phases during the repolarizing period. We observed a high correlation between Vphase1 and the amplitudes of either depolarization or repolarization phases. Human thalamic nuclei differ in their electrophysiological properties of APs, even under general anesthesia. Capacitive current, which is probably responsible for Vphase1, is very common in thalamic APs. Moreover, subtle differences during repolarization are neuron-specific.

The traditional current differential protections for HVDC transmission lines are easily affected by distributed capacitive current. Although some improved differential principles have been presented in literatures, they still risk maloperation caused by synchronization error, noise or parameter errors. To overcome the problems above, this paper proposes a novel pilot protection scheme based on waveform matching. After the electrical quantities on both sides are low-pass filtered, the HVDC line is simplified to two PI models from the midpoint, which can eliminate the effect of distributed capacitive current and has simple computation as well as satisfying precision. The midpoint currents, which can be calculated based on the simplified DC line model with the information of either side, will be matched under external faults while have opposite trend under internal faults. The improved Pearson correlation coefficient (IPCC) is proposed to measure the similarity between the waveforms of the calculated midpoint currents and establish the protection criterion. A ± 800 kV HVDC test system is modeled in PSCAD/EMTDC. Extensive simulations of various fault situations indicate that the new protection has absolute selectivity, great reliability and strong fault resistance withstand ability. Sensitivity analysis and comparisons with other pilot protections further demonstrate that the proposed protection stands out for high accuracy and strong robustness to many non-ideal factors.

Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.09.13 – техніка сильних електричних та магнітних полів. – Національний технічний університет України «Київський політехнічний інститут імені Ігоря Сікорського» МОН України, Київ, 2019. У дисертації вирішено актуальне наукове завдання розвитку методів математичного моделювання процесів автотрансформаторного перетворення високої напруги, визначення його характеристик на основі використання чисельних розрахунків електричних та магнітних полів та удосконалення відповідних високовольтних вимірювальних пристроїв. Деталізовано системи рівнянь високовольтних автотрансформаторів напруги та випробувальних трансформаторів до рівня одиничних витків (або груп витків) обмоток, що дозволяє з високою точністю розраховувати їх характеристики трансформації напруги при коефіцієнтах масштабного перетворення до 100000 одиниць і більше. Виявлено не пояснену раніше зміну масштабного коефіцієнта у високовольтних випробувальних трансформаторах з комплексним трансформаторним та автотрансформаторним перетворенням напруги за різного характеру навантаження та запропоновано спосіб коригування даної зміни. За обгрунтованими в дисертації теоретичними положеннями розроблено, виготовлено та метрологічно атестовано нові зразки високовольтної вимірювальної техніки, в яких використовується автотрансформаторне перетворення напруги. Thesis for a candidate degree (PhD) in specialty 05.09.13 "Technics of strong electric and magnetic fields". National Technical University of Ukraine "Igor Sikorsky Kyiv Polytechnic Institute", Ministry of Education of Ukraine, Kyiv, 2019. The thesis agreed relevant scientific task of the development of mathematical modeling methods of high-voltage autotransformer conversion processes, determine its characteristics through the use of numerical calculation of electric and magnetic fields and the corresponding high-voltage measuring devices, including the achievement of a significant improvement in their accuracy. In the first chapter of the thesis performed a review of the literature related to the subject of research. A review of the literature and current scientific research has allowed revealing a number of outstanding issues relating to the autotransformer voltage conversion in high voltage measuring devices. In the second chapter of the thesis expounded the scientific achievements of the author concerning the autotransformer conversion of high voltage in modes close to the idling mode, the influence of capacitive currents that occur in multilayer windings of high-voltage measuring autotransformers, the voltage distribution along the winding turns. The method that allows to calculate the leakage inductance of the winding by simulation of the high-voltage autotransformer active part in the cylindrical coordinate system, excluding components of leakage flux linkage in rod magnetic core section, which allows to determine the present equivalent leakage inductance of the high-voltage measuring autotransformers windings as the difference values of one order (in relation to the value that is defined). Method for determination of those turns location coordinates of the low-voltage winding part of high-voltage autotransformer, which is based on the achievement of predetermined set value given the equivalent leakage inductance of its winding, that need to get for the high-voltage autotransformer that is projected. Mathematical model of high-voltage autotransformer in the cylindrical coordinate system is improved by taking into account the components of magnetic leakage flux linkage in different parts of the plane of the winding cross section. The use of fractional coefficients "rod" and "yoke" leakage flux linkage is suggested, allowing closer compliance with the parameters of the leakage flux linkage of the complex axisymmetric model's winding and the three-dimensional model of high-voltage autotransformer. The influence analysis of capacitive currents in high-voltage windings of autotransformers on voltage distribution along the turns of their layers is performed. Found their nonlinear character and vector diagram for calculating the contribution of capacitive current in voltage distribution along the turns of high-voltage measuring autotransformer. In the third section of the dissertation examined the theory of the test transformers that use complex transformer and autotransformer voltage conversion, for example the high-voltage testing transformer with high-voltage winding, built by the scheme of autotransformer voltage conversion. Special attention is paid to the issue of autotransformer high-voltage conversion at different test load of this transformer. Defined features modes such high-voltage test transformer when significant capacitive load and the proposed method of correcting error of autotransformer high-voltage conversion in them. Added to the theory of autotransformers the equation systems, that allowed determining the voltage distribution in windings at the level of the single turns or groups of turns. In the fourth chapter of the thesis performed a comparison of the characteristics calculation results of autotransformer high-voltage transformation by the theoretical provisions set out in the second and third sections of this thesis, with the results of experimental research. Performed a comparison of the experimentally obtained data of voltage distribution along winding turns of 10 kV reference high-voltage autotransformer with the results of theoretical calculations on the proposed in thesis complex mathematical model of the windings. Performed a comparison of the experimentally obtained data, coefficients of voltage scale conversion of high-voltage testing transformer with winding, built by the scheme of autotransformer voltage conversion, with different types of it loads (including using the proposed method, the adjustment factor for autotransformer high-voltage conversion) with the results of theoretical calculations made by the autotransformer system of equations in a dissertation. Диссертация на соискание учёной степени кандидата технических наук по специальности 05.09.13 – техника сильных электрических и магнитных полей. Национальный технический университет Украины «Киевский политехнический институт имени Игоря Сикорского» МОН Украины, Киев, 2019. В диссертации решена актуальная научная задача развития методов математического моделирования процессов автотрансформаторного преобразования высокого напряжения, определения его характеристик на основе использования численных расчетов электрических и магнитных полей и усовершенствования соответствующих высоковольтных измерительных устройств. Детализированы системы уравнений высоковольтных автотрансформаторов напряжения и испытательных трансформаторов до уровня единичных витков (или групп витков) обмоток, что позволяет с высокой точностью рассчитывать их характеристики трансформации напряжения при коэффициентах масштабного преобразования до 100000 единиц и более. Обнаружено не объясненную ранее причину изменения коэффициента масштабного преобразования в высоковольтных испытательных трансформаторах с комплексным трансформаторным и автотрансформаторным преобразованиями напряжения при различном характере нагрузки и предложен способ корректировки изменения этого коэффициента. С помощью обоснованных в диссертации теоретических положений разработаны, изготовлены и метрологически аттестованы новые образцы высоковольтной измерительной техники, в которых используется автотрансформаторное преобразования напряжения.

Two experimental methods to estimate the electrochemically active surface area (EASA) of microelectrodes are investigated. One method is based on electrocapacitive measurements and depends significantly on the surface roughness as well as on other parameters. The other method is based on faradaic current measurements and depends on the geometric surface area. The experimental results are supplemented with numerical modeling of electrodes with different surface roughness. A systematic study reveals a strong influence of the scale and arrangement of the surface roughness, the measurement potential and the electrolyte concentration on the EASA of microelectrodes estimated from the electrocapacitive measurements. The results show that electrocapacitive measurements should not be used to estimate the faradaic EASA of microelectrodes with a non-negligible surface roughness.

Предложена и реализована схема устройства, предназначяенного для снижения влияния импульсных перенапряжений и токов., A scheme of a device designed to reduce the influence of surge surges and currents is proposed and implemented.

In order to solve the problems that the conventional back-up protection for HVDC (High Voltage Direct Current) transmission lines fail to respond to internal faults quickly, an improved back-up protection scheme was proposed in this study. If voltage and current signals at both sides of the DC line are filtered by the low-pass filter and the cut-off frequency is low enough, then the distributed parameter model of the line can be equivalent to Π model. Based on the Π model, the filtered differential current of the non-fault line is proved to be always smaller than the maximum capacitive current. According to the above analysis, the new differential protection criterion was implemented. A ±800kV HVDC transmission system was built to test the performance of the new protection scheme. Comprehensive test studies show that the proposed method not only can detect internal faults and select the fault lines correctly and quickly, but also respond to internal faults with high transition resistance.

In general, LED drivers with a passive current balancing function are cheaper and smaller than active current balancing drivers thanks to the lack of current sensors and control circuits. Conventional passive current balancing drivers, however, tend to suffer from its poor extendibility because a multi-winding transformer is required for the extension of the LED strings. Although capacitive current balancing LED drivers with no multi-winding transformer achieve high extendibility, numerous capacitors are necessary for extension process. In this paper, a highly-extendable capacitive current balancing multichannel LED driver is proposed. Not only can the number of LED strings be arbitrarily extended by adding capacitors and diodes, but also the capacitor count can be reduced compared to the conventional capacitive current balancing LED drivers. The operation analysis and current balancing mechanism are discussed in detail. The experimental verification using a prototype for eight LED strings demonstrated the efficacy of the proposed LED driver.

In the traditional model predictive control(T-MPC), only inverter side current of LCL inverter is treated as a control target. Grid side current is controlled indirectly by controlling the inverter side current directly. The control performance of the algorithm can be further improved. In this paper, a complete model predictive control algorithm(C-MPC) which take the grid side current as control target directly is proposed. The equivalent mathematical model and the equivalent circuit model are established based on active damping of capacitive current proportional feedback, then system predictive control model is established by the equivalent mathematical model and the circuit model. In order to make the output current track the directive current accurately at the next moment, the output voltage vector needed at this moment is calculated by the predictive control model. Finally, the required voltage vector is reproduced through space vector modulation(SVM). The simulation results and experimental measurements verify the developed control schemes and show high quality of grid side current (low THDi value).

It is shown that the mean value of the capacitive current arising in the p-n-junction in a microwave field is zero, and the average value of the active current independently of the current value is different from zero and is equal to the current generated by the diode.

Back-to-back capacitive bank switching is the most severe duty among capacitive current switching duties because the amplitude of the inrush current with high frequency is very large. In this paper, 36kV back-to-back capacitive current switching tests of test duty 2(BC2) were carried out with vacuum circuit breaker. And the tests were performed with a series of separate making tests of 120 operations followed by a series of CO tests of 120 operations due to limitations of the test plant according to IEC standards 62271-100. The two types of VCB were tested with single phase and the test results were compared in terms of pre-arcing time, break down voltage distribution, contact surface after tests, contacting area, and field enhancement factor.

Capacitive current switching test is an important test for high voltage ac circuit breaker. In recent years, many problems, such as frequent restrikes under special environment condition and non-sustained disruptive discharge (NSDD) and restrike after more than one cycles of recovery voltage, were met when ultra (extra)-high voltage circuit breaker switching capacitive current in system and test. In this paper, these typical problems are researched and analyzed, the imperfections of current relevant standards and test methods are discussed, the new tests and experiences of the circuit breaker used for switching filter bank are introduced. This paper is a meaningful exploration for the improvement of the current standards and test methods.

DNA is usually composed of several nucleotide and form as a spring shape with good elasticity. It has been observed that DNA can be extended by external forces, such as magnetic or electric fields from literature. Through the changes of electric field, DNA can be deformed by electrical force. DNA can be compressed or stretched like a spring and store energy. When the applied forces disappear, the stored energy is released and DNA switch back to the original shape, leading to the capacitive current induced by the DNA motions. The capacitive current is recorded before the DNA fully relaxed. In this study, dsDNA was intercalated with different concentrations of Doxorubicin, causing different relation of DNA motion, and further leading to different capacitive current level. Doxorubicin is one of the commonly used drugs for cancer therapy, and it is only intercalate between G-C base pairs in dsDNA. In this study, it can be developed as a new type of biosensors and also facilitate the fundamental understanding of the dsDNA characteristics. Figure 1(a) shows the schematic of device. The devices grew 3000 Å-thick SiNx on silicon wafer for dielectric layer, and plated 1000 Å-thick Au for electrodes. The sequence of the single strand DNA (ssDNA) and the Cy3 dye- attached complimentary DNA (Cy3-cDNA) are shown as 5'- thiol-TTT GCT TTT TCG TCG TTT GCT TTT CGT TTT- thiol- 3' and 5'-(Cy3)-AAA ACG AAA AGC AAA CGA CGA AAA AGC AAA-3', respectively. The Cy3-dsDNA solution was prepared by mixing and preparing 5 μM ssDNA, 5 μM Cy3-cDNA and 5 mM TCEP together in a 30 mM phosphate buffer solution (pH=8), followed by being heated to 90 ºC lasting for 2 minutes. The heated DNA solution was then gradually cooled down to room temperature to allow the hybridization of dsDNA. The hybridized dsDNA solution was then dropped on the gold substrate and waited for 36 hours in 25 ºC. Figure 1(b) shows the schematic of different pulse width. The bias applied for measuring the capacitive current was 0.5 V. Figure 2 shows the capacitive current of dsDNA sample measured in different pulse widths. In short pulse (pulse width < 1 ms) width measurement, the capacitive current was recorded before the DNA fully relaxed. In long pulse width measurement (pulse width > 10 ms), the capacitive current was measured after dsDNA fully relaxed. Figure 3 shows the capacitive current measured when different concentration of Doxorubicin intercalating into dsDNA in 500 μs pulse width. As dsDNA molecule intercalated by higher concentration of Doxorubicin, the capacitive current was decreased with higher concentration of Doxorubicin. In summary, different pulse widths affect the types of energy stored in dsDNA. And the stored energy is further manifested in different capacitive current. The relation between the stored energy and the capacitive current can be further confirmed by comparing with the sorter pulse widths measurement in the future. This work was partially supported by National Science Council grant (101-2221-E-007-102-MY3) and by the research grant (101N7047E1) at National Tsing Hua University.

currently, more and more following-setting compensation arc suppression coils are applied. When the power distribution network is operated in a loop closing mode, the problems about the parallel operation of the following-setting compensation arc suppression coils are caused. On the basis that the operational characteristics of the following-setting compensation arc suppression coils are analyzed, the improved master-slaved type automatic control technology of the parallel operation of the multiple following-setting compensation suppression coils is proposed. When the capacitive current is calculated, all slave arc suppression coils should go into service with the respective compensating capacity of each when operated on the respective shunt, then the master arc suppression coil is adjusted, and therefore the calculation accuracy is guaranteed. After the calculation of the capacitive current is completed, the compensating current should be proportionally distributed according to the capacity of the arc suppression coils so that the loads of all the arc suppression coils are balanced. The technology is mature and reliable and the practicability of the technology is fully proved by the actual field operation. Chinese library classification number: TM475;TM761

Nowadays, an increasing number of grid is adopting resonant grounding method. Only accurately detecting the capacitive current, could we play the advantages of resonant grounding. The most popular method in the field is the tuning method, which includes two-point method and three-point method. This paper analyzes the principle of two-point method and identifies a major problem in the application of two-point method. A stall of two-point method stays in the state of overcompensation while another stall stays in the state of under compensation, which has not been taken into account. Finally, the paper verifies the effect of proposed improvements using MATLAB simulation.

In most occasions shunt APFs and capacitors used for power factor correction exist simultaneously in the distribution network for saving costs. Ideally, APFs are used for harmonics filtering and capacitors are used for power factor correction. However, traditional control methods of APF have potential risk of resonance, affecting the stability and the effect of harmonic compensation, if the detected current contains capacitive current. This paper proposes a new control method based on voltage detection of point of common Coupling(PCC). Theoretical analysis and simulation demonstrate the new control method has functions of resonance suppression and harmonic filtering

On-line monitoring of the insulating state of metal oxide surge arresters (MOA) is monitoring its resistive leakage current. This paper analyses the common detection methods of resistive current, pointed out the problems. According to the relationship among the grid voltage and the flow through the leakage current of MOA, the resistive and capacitive current, put forward a new resistive leakage current detection method, and established a mathematical model. Using this mathematical model, new detection method can be verified by simulation. Confirmed that the new method can effectively reduce the impact of the power grid of the third harmonic voltage and phase coupling capacitor, this create a precise measurement for MOA resistance current online testing.

Combined with actual situation of Fengxian power Supply Company, the neutral grounding modes of Fengxian 35 kV and 10 kV power grid are studied in the paper. The different frequencies injected method is used to measure the capacitive current of Fengxian 28 substations, and the neutral grounding modes of the 28 substations are determined based on the measured values of capacitive current.

The use of nanofluidic devices for ultrasensitive electroanalytical applications is at the forefront of emerging detection techniques. These devices generally incorporate two individually addressable electrodes embedded within a nanochannel and are well suited for performing highly efficient redox cycling–repeated oxidation and reduction to amplify the electrochemical signals, enabling detection and quantification of the analyte molecules. The small capacitive current and steady-state voltammetric response offered by these devices makes them ideal systems for single molecule electrochemical detection. In this chapter, the concept of redox cycling employed in nanofluidic devices along with their fabrication strategies and applications relevant to electrochemistry is summarised.

Back-to-back capacitive bank switching is the most severe duty among capacitive current switching duties because the amplitude of the inrush current with high frequency is very large. In this paper, 36kV back-to-back capacitive current switching tests of test duty 2(BC2) were carried out with vacuum circuit breaker. And the tests were performed with a series of separate making tests of 120 operations followed by a series of CO tests of 120 operations due to limitations of the test plant according to IEC standards 62271-100. The two types of VCB were tested with single phase and the test results were compared in terms of pre-arcing time, break down voltage distribution, contact surface after tests, contacting area, and field enhancement factor.

The faults of arc suppression coil appearing often in the course of work are described and the nature of the faults is divided in this article. The different faults as general failure, arc suppression coil abnormal failures, malfunctions and the arc suppression coil disable failure are discussed and studied, and the appropriate treatment scientifically are given.

The paper presents the analysis of main reasons and consequences of the decrease of the efficiency for suppression of single phase-to-ground faults causing dangerous technological failures and faults in distribution networks. Advantages and disadvantages of main systems for partial or full compensation of a ground fault current used for minimizing losses are described. Comparative calculations on the emergency tripping probability due to the development of a single phase-to-ground fault into phase-to-phase short circuit in compensated and ungrounded networks are given. Based on the experience of manufacture and operation, technical requirements to arc suppression devices and their compensation automation systems are developed.

Виконано аналіз розподілу ємнісних струмів в витках багатошарових обмоток високовольтних автотрансформаторів напруги. Визначено відмінність розподілу ємнісних струмів для першого шару витків та всіх інших шарів обмотки. Запропонований метод врахування впливу ємнісних струмів в обмотці високовольтного автотрансформатора напруги на розподіл загального спадання напруги по витках обмотки., Проанализировано распределение емкостных токов в витках многослойных обмоток высоковольтных автотрансформаторов напряжения. Выявлено различие распределения емкостных токов для первого слоя витков и всех остальных слоев обмотки. Предложен метод учета влияния емкостных токов в обмотке высоковольтного автотрансформатора напряжения на распределение общего падения напряжения по виткам обмотки., The paper analyzed the distribution of capacitive currents in the winding of measuring high-voltage autotransformer at its operating frequency 50 (60) Hz. It is revealed that idling high-voltage autotransformer at significant nominal dividing coefficient these currents can acquire essential values against the current idling, which can affect the accuracy of large-scale conversion of high-voltage measuring autotransformers. The paper presents an approach to account values of interlayer capacitive currents in the windings of high-voltage autotransformers to clarify the distribution of voltage on their low-voltage (output) winding parts. It is shown that the distribution of capacitive currents significantly different to the first, last and middle layers of windings that must be considered when designing the windings of high-voltage autotransformers and calculate the number of turns in the respective high-voltage and low-voltage parts of windings. This analysis is particularly important for the development of standard measurement tools using high-voltage autotransformer scale transformation.

In this paper a new approach of ground fault capacitive current compensation in ungrounded distribution networks is proposed. According to proposed method in parallel with network phases a static semiconductor converter is connected. In the ground fault mode the converter must generate the current of zero sequence in opposition with capacitive short circuit current. In this paper the electromagnetic processes taking place in the network in a short circuit mode are considered, and also the possibility of ground fault capacitive current compensation in the short circuit mode by static converter is shown. The converter simulation results with Matlab Simulink in the short circuit mode are presented.